An organic light-emitting element is composed of two opposing electrodes and organic material thin films of a plurality of layers having semiconductor-like properties interposed therebetween. The organic light-emitting element having the configuration uses a phenomenon in which electric energy is converted into light energy by using an organic material, that is, an organic light emission phenomenon. Specifically, when voltage is applied between two electrodes in a structure in which an organic material layer is disposed between an anode and an electrode, holes from the anode and electrons from the cathode are injected into the organic material layer. When the injected holes and electrons meet each other, an exciton is formed, and the exciton falls down to a bottom state to emit light.
In the aforementioned organic light-emitting element, light generated from the organic material layer is emitted through a light transmissive electrode, and the organic light-emitting element may be typically classified into a top emission type, a bottom emission type, and a double-sided emission type. In the case of the top emission or bottom emission type, one of two electrodes needs to be a light transmissive electrode, and in the case of the double-sided emission type, both the two electrodes needs to be a light transmissive electrode.
In respect to the aforementioned organic light-emitting element, many studies have been conducted since Kodak Co., Ltd. announced that when a multilayer structure is used, the element may be driven at a low voltage, and recently, a natural color display using an organic light-emitting element is attached to a mobile phone and commercialized.
Further, as recent studies on the organic light-emitting element using a phosphorescent material instead of a fluorescent material in the related art have been conducted, efficiency has been rapidly improved, and it is also expected that the element would be able to replace an illumination in the related art in the near future.
In order to use the organic light-emitting element as illumination, the element needs to be driven with high brightness unlike the natural color display in the related art, and a constant brightness needs to be maintained like the illumination in the related art. In order to sufficiently improve the brightness of the organic light-emitting element, light emission needs to be implemented in a large area, and in order to implement light emission in the large area, a high driving current needs to be used. In addition, in order to maintain constant brightness in the large area, the aforementioned high current needs to be uniformly injected into the element having the large area.
In general, an organic light-emitting element for illumination has a structure in which a transparent electrode, an organic material layer, and a metal electrode are sequentially deposited on a substrate. When the organic light-emitting element is produced, the organic material layer and the deposition pattern of the metal electrode have different areas on a plan view, and thus different masks are used when the organic material layer and the metal electrode are deposited. Accordingly, there are problems in that it is necessary to replace the mask during the deposition process, productivity is not high due to complex vapor deposition equipment, and production costs are also high.
Currently, a generally-used cluster type deposition apparatus includes a mask for an organic material layer or a mask for a metal electrode per deposition chamber, and when a substrate is introduced into the deposition chamber, the mask and the substrate are combined and then an organic material or metal is deposited thereon. In the process, the number of masks only increases proportionally to the number of deposition chambers. In such a mode, a time for transferring the substrate, a time for combining the substrate and the mask, a time for depositing the organic material or metal and the like, are required, and thus there is a limitation on improving productivity.
On the contrary, in the case of in-line vapor deposition equipment, most of the preparation processes may be omitted, and thus an opportunity to improve productivity is inevitable. However, there is a problem in that even the in-line vapor deposition equipment needs the number of masks that is equal to or more than the number of all the substrates that are inputted into the deposition chamber and on which deposition is performed. When an organic material deposition pattern and an inorganic material deposition pattern are different from each other, the number of masks required needs to be double or more the number of substrates. Furthermore, while the organic material deposition process is changed into the metal electrode deposition process during the in-line process, a mask replacement process is needed, and productivity may be reduced during the procedure.
In order to implement mass production of an organic light-emitting element for illumination in the future, there is a need for a study that may increase productivity of an organic light-emitting element without a mask replacement process in the in-line vapor deposition equipment.